View Full Version : Early Lansing Ampex 5050 Speaker System

09-14-2005, 04:06 PM
Anyone know anything about these or have a photo? Remember seeing one on Ebay for something like 17 grand. Unique design. Ever heard one ?

Came with super early 375 drivers, 537-500 horns, and 150-4 woofers.

Just curious ........ Would make a neat winter project. :blink:



House de Kris
09-15-2005, 04:53 PM
I've got a couple 5050 cabinets sitting in my garage. I've asked here before for info on them and drew a blank. What sort of info are you seeking?

Here's a picture of the plate on the back.

09-15-2005, 08:03 PM
Well.............. drawings, blueprints, dimensions, etc.... Got any more pictures ? How do they sound? How rare are they?



09-15-2005, 11:21 PM
I think that those speakers were part of the Todd-AO Cinemascope multi-track motion picture sound reproduction system that used a magnetic tape strip on the edge of the film. Ampex supplied the whole thing, pickups, amps, speakers.

It is said that Ampex actually built the components using the JBL designs, themselves, it is hard to believe that they would have tooled up to make all those pieces themselves for such a limited run, but what do I know.

Don McRitchie
09-16-2005, 06:13 AM
Well.............. drawings, blueprints, dimensions, etc.... Got any more pictures ? How do they sound? How rare are they?


09-16-2005, 01:18 PM
Hey Don,

thanks for the photo. Ever seen one or heard one? How rare are they?

Thanks again,:applaud:


09-16-2005, 01:38 PM
Hey Don,

looked at that link, and the photo you posted is closer to the Westrex 5208 blueprints I've got - not the Ampex 5050 cabinets I referred to in another post.

It says right on one of those drawings - "Westrex T500 Series" and "T510A Low Frequency Speaker". It also says they were 150-4W's, 32 ohms, and the year 1953.

The JBL / Ampex 5050 cabinets I saw on Ebay were about the size of an Altec A7 cabinet - maybe a little smaller - and had the "potato masher" horns, and two 15's (150-4's) side by side on the front of the speaker, but NOT in the same plane. The cabinet had a slight "V" to the front of it and the 15's were pointing off at different angles. In other words, they were not mounted on the same board facing directly forward. They were not mounted in the same plane. I've got a copy of the auction around here somewhere but can't find it at the moment.



House de Kris
09-16-2005, 02:36 PM
RacerXtreme, is the attached picture from the auction? I stole this pic off of eBay. The picture without the drivers are my cabinets.

Like I mentioned, I've got two cabinets in my garage. Never had drivers in them, so I can't comment on how they sound. Mine have the wacky front panel with the drivers not in the same plane. Have no drawings or other whatnot, all I know is that they weigh over 200lbs each empty. I didn't get the potato masher horns either, just the bass cabs. Hmph, not a whole lotta help, am I?

As I understand it, the 5050 evolved into the C-55, then into the 4520. The horn path length may have changed during these evolutions.

09-16-2005, 06:46 PM
The ones I saw on Ebay were blue if I remember correctly, but yes, those are exactly the cabinets I was talking about.

Never listened to them tho? Wonder what they sound like......

Thanks for the photos. :applaud: What are their dimensions?



Don McRitchie
09-17-2005, 11:16 PM
I wrote my previous reply quickly on the road without access to my archive. I should know better by now not to jump in so quickly. In hindsight, I believe the Ampex model number for that system was 6000 and obviously not 5050. It did use 375 drivers, 537-500 horns and 150-4 woofers as in the original post. I was told that Bill Thomas himself had a hand in the design of the 6000 since the bass horn had application to his defense industry business. The system was marketed under three brand names, the JBL Theatre System, the Westrex T550 and the Ampex 6000. BTW, Ampex most certainly did manufacture 375's and 150-4C's under license from JBL. Their relationship was so close that Ampex negotiated a buyout of JBL, which Bill Thomas only declined at the last minute.


Steve Schell
09-18-2005, 09:47 AM
I can add a little to what Don said. Ampex made a major effort to penetrate the theatre sound business in the 1950s, and chose JBL to provide the speaker systems. Westrex (export arm of Western Electric) was also looking for a supplier of theatre sound gear, since Western Electric had recently ceased making this equipment due to a consent decree with the U.S. Government. They also chose JBL to make much of their equipment.

The 375 driver was developed to meet the need for a stout high frequency driver for these systems. We have heard conflicting stories as to who actually initiated the design effort, but it is evident that they were being supplied to the two companies by 1953 if not earlier. Actually Ampex was ordering more product than JBL, still a small company at te time, could supply. To meet their need, they opened their own factory in North Hollywood and built their own versions of the JBL products, paying JBL a royalty on each unit produced.

I think that the Westrex 375s were built by JBL, as they look very similar to the early bubble back units used in the Hartsfield. Note that the 375 had been developed for theatre, not hi fi use. The Ampex products for certain, and likely the Westrex products as well, were in production well before the 375 was applied for hi fi use with the introduction of the Hartsfield in 1954.

09-14-2008, 05:52 PM
I am quite familiar with these 5050 enclosures. From 1982 until 2003 I was employed maintaining the military theaters in the Pacific region. When I left in ’03 there were still a handful of small theaters using these on a daily basis. And with the original drivers too! Testament to their good design. We only needed 20 Watts of power to drive them. The 15 inch low frequency drivers are 32 ohms connected in parallel.

I think the reason we cannot find a decent paper trail on these is that they may have been a special product made just for the military.

The paperwork that I have seen on them (stapled to the back) list them as a “kit” to be assembled on site. The shipping date on one has it leaving the states in 1951. The kit contained the birch plywood sections, 2 x 4 members for the elevated stand, the drivers, the passive crossover and a baffle (three sections) for the sides and bottom. The stand raised the whole unit so that the HF driver was at screen center. There was also a screen kit but that’s another story.

These things are very heavy. They produce decent sound. With the baffle installed it can easily fill an auditorium. They even work well outdoors in open air but be sure to have the baffle in place otherwise the low frequencies will wrap around the back and cancel out. In operation the rear and sides of the cabinet do not vibrate. If you knock on it it sounds like you are knocking on a granite counter top. Very solid.

Where the two opposing LF drivers mount there is some clever internal ducting. I’m guessing this was to merge the two sound fields into one with additional pressure. Then the sound was routed through a very small throat before it passed into the folded horn. Right angles were eliminated internally by use of triangular fillers where plywood sections meet. There was also a model with only one 15 inch driver in a flat plane but I do not know the model number of that one. Our smaller down range theaters used that one.

The sound waves emanating from the horn are 180 degrees out from the drivers but somehow it all works. With the original drivers it will not go very low but you could always update things here to your liking.

All the 5050s I have seen used the HF horn driver attached to an Ampex horizontal horn made from what looks like cast iron.

I’m not sure about the $17K price tag mentioned here. Maybe for two with the original drivers still intact that would be appropriate. But what you have here are two plywood boxes. The only thing of real value is the nameplate. BTW the original drivers all had the same Lansing “signature” label attached to them with no mention of Ampex. Only the exterior nameplate mentions Ampex.